Quick release hoist system

ABSTRACT

A hoist system including an air balancer having an air supply and an air exhaust, a lifting device, and a hoist control pendant to control supply and exhaust of pressurized air to and from the air balancer, respectively, the hoist control pendant configured to control vertical movement of the lifting device. The air exhaust from the air balancer includes a first exhaust flow path through a first exhaust opening and a second exhaust flow path through a second exhaust opening, the first exhaust flow path having a first length and the second exhaust flow path having a second length, the second length being shorter than the first length.

BACKGROUND 1. Field of the Disclosure

The present disclosure relates to hoist system and, more particularly,to a pneumatic hoist system with a quick release mechanism.

2. Description of Related Art

Pneumatic balancing hoists are well established as a standard in thematerials handling industry. These pneumatic balancing hoists or airbalancers, have been used for years to move work pieces about a factoryor industrial site. Pneumatic balancing hoists are also used in anassembly line operation to facilitate the placement of multiplecomponents in a machine or device. The process time on the assembly linecan include a number of assembly steps such as, for example, the timefor the hoist to retrieve the component from a conveyor, the time forthe operator to install the component, and the time for the hoist to bereleased from the installed component and move back to the conveyor torepeat the component retrieval process. Each of these assembly steps canbe a potential issue for desired cycle time not being achieved.

After the component has been installed, the air within the pneumatichoist must be exhausted so that there is sufficient slack in the hoistcable for release from the installed component and the hoist can thenmove downwards back towards the conveyor. Typically, however, exhaust ofthe air is limited to an exhaust port in the hoist control pendent,thereby requiring the air to travel the length of the airline from thehoist to the control pendant before it can be exhausted.

There is a need in the art for a system and method that decreases therelease time of a pneumatic hoist in an effort to improve overall cycletime in an assembly line operation.

SUMMARY OF THE INVENTION

According to the disclosure herein, a “quick exhaust” system is added toa pneumatic hoist utilizing a plurality of pilot valves. The quickexhaust system allows a user to temporarily bypass the exhaust throughthe pendant control once a load (i.e., the component to be moved) is nolonger on the hoist and utilize an exhaust port provided by the pilotvalve. The quick release of pressure to lower the hoist can be improvedby increasing the air flow on the exhaust side of the hoist. Hence, theexhaust port provided by the pilot valve allows the air from the hoistto exhaust more quickly and thus improves the release time and overallcycle time for the hoist operation.

In one aspect, the disclosure provides a hoist system having an airbalancer having an air supply and an air exhaust; a lifting device; anda hoist control pendant to control supply and exhaust of pressurized airto and from the air balancer, respectively, the hoist control pendantconfigured to control vertical movement of the lifting device. The airexhaust from the air balancer includes a first exhaust flow path througha first exhaust opening and a second exhaust flow path through a secondexhaust opening, the first exhaust flow path having a first length andthe second exhaust flow path having a second length, the second lengthbeing shorter than the first length.

The disclosure herein further provides an air balancer for a pneumatichoist system having a housing including opposing end walls and acylindrical casing extending therebetween; a piston slidably disposedwithin the cylindrical casing so as to define an air chamber proximateone of said opposing end walls; a mechanical linear actuator extendinglongitudinally through the housing and actuated by the piston; an inletfor air to be supplied into the air chamber; and an exhaust systemcontrolling air to be exhausted from the air chamber. The exhaust systemdefines a first exhaust flow path and a second exhaust flow path, thesecond exhaust flow path exhausting a greater volume of air than thefirst exhaust flow path in a predetermined period of elapsed time.

In another aspect, the disclosure provides a method of pneumatic hoistoperation including providing a pneumatic hoist having an air balancer,a lifting cable hoist, and a hoist control pendant, wherein the hoistcontrol pendant includes an up direction control, a down directioncontrol, and a quick release down control; actuating the up control onthe hoist control pendant to raise the lifting cable in an upwardsdirection; actuating the down control on the hoist control pendant tolower the lifting cable in a downwards direction at a first rate ofdescent; and actuating the quick release control on the hoist controlpendant to lower the lifting cable in a downwards direction at a secondrate of descent; wherein the second rate of descent is greater than thefirst rate of descent.

Other systems, methods, features and advantages of the disclosure willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the disclosure, and be protected by the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the disclosure. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 is a schematic view of a quick release pneumatic hoist systemaccording to an exemplary embodiment of the disclosure illustrated in anassembly line for installing a component onto a machine.

FIG. 2 is a partial cut-away view of an air balancer for the quickrelease pneumatic hoist system according to an exemplary embodiment ofthe disclosure.

FIG. 3 is a schematic view of a hoist control pendant for the quickrelease pneumatic hoist system according to an exemplary embodiment ofthe disclosure.

FIG. 4 is a schematic end view of the air balancer for the quick releasepneumatic hoist system according to an exemplary embodiment of thedisclosure.

FIG. 5 is an air flow schematic for the quick release pneumatic hoistsystem according to an exemplary embodiment of the disclosure.

DETAILED DESCRIPTION

Heretofore, pneumatic hoists have usually relied upon the hoist controlpendant to exhaust air from the hoist. The exhaust port in the controlpendant requires the air to travel an extended distance from the airbalancer to the control pendant, for example, approximately 12 feet orso. This extended air flow path to reach the exhaust port thus impedesthe overall assembly line process because it slows down the time torelease the hoist from the component being moved, and thereby decreasesthe cycle time for the hoist operation. According to the disclosureherein, a “quick exhaust” system is added to a pneumatic hoist utilizinga plurality of pilot valves. The quick exhaust system allows a user totemporarily bypass the exhaust through the pendant control once a load(i.e., the component to be moved) is no longer on the hoist and utilizea relatively close, nearby exhaust provided by the pilot valve. Thenearby exhaust valve allows the air from the hoist to exhaust morequickly and thus improves the release time and overall cycle time forthe hoist operation.

A hoist system according to an exemplary embodiment of the disclosure isshown generally in FIG. 1 by reference numeral 10. The hoist system 10includes an air balancer 12 operated by a hoist control pendent 14.Extending downward from the air balancer 12 is a suspension structuresuch as a hoist lifting cable 16, chain, or similar support mechanismconnecting the air balancer 12 to an associated handling device 17 formoving the load or component 18. An overhead support such as a trolleymovable on a rail or track system or some other fixed or movablestructure (not shown) connects to the housing 20 at a suspension lug 26or similar connection element. In particular, such a hoist system 10 canbe used to raise a component 18, such as a transmission T, from aconveyor C, slide the component 18, onto a machine such as an engine E,and then release the handling device 17 from the component 18 so that itcan be lowered back to the conveyor C and the cycle can be repeated. Themovement of a component 18 with such a pneumatically-operated hoist iswell-known in the art.

Referring also to FIG. 2, the air balancer 12 includes a housing 20having opposing end walls 22, 24 and a hollow cylindrical casing 28therebetween. A mechanical linear actuator that translates rotationalmotion to linear motion, such as ball screw 30, extends longitudinallythrough the housing 20. A ball screw assembly 32 is mounted on the ballscrew 30 and moves longitudinally within the housing 20 when turnedrelative to the ball screw 30. Ball screw assemblies 32 of this natureare well-known in the art and no further discussion is required herein.A rotating cable drum or reel 34 is mounted on the ball screw assembly32 and moves on the ball screw 30 both rotatably and longitudinallyrelative to the ball screw 30. The rotating cable reel 34 has a shallowhelical groove 36 that receives the lifting cable 16 when the component18 is raised and the lifting cable 16 is wound on the rotating reel 34.As the reel 34 moves rotatably and longitudinally within the housing 20,the lifting cable 16 is wound or unwound about the rotating cable reel34 for raising and lowering loads. Whether the lifting cable 16 is woundor unwound will obviously depend on the direction of the movement of theload being up or down. The lifting cable 16 exits through a housingaperture 38 to the handling device 17 or a hooking mechanisms of anytype used for attachment to the component 18 to be moved.

A hub portion 40 of the rotating cable reel 34 is mounted on anextension of the rotating cable reel 34 in order to bear against apiston 42. The piston 42 slides on the inner surface of the casing 28 soas to tightly seal the air in a chamber 44 formed within the housing 20.Hence, the end wall 24, the cylindrical casing 28, and the piston 42define an air chamber 44 within the housing 20 to receive air foroperating the hoist system 10. When pressurized air is supplied to thechamber 44, the piston 42 is moved longitudinally through the housing 20and forces the rotatable cable reel 34 and the ball screw assembly 32 inthe same longitudinal direction, i.e., from right to left as illustratedin FIG. 2. During this longitudinal movement of the piston 42, the ballscrew assembly 32 also causes the reel 34 to rotate in a manner to raiseand lower the lifting cable 16 and the attached load or component 18.The flow of pressurized air supplied to and expelled from the chamber 44is discussed in further detail below. Further, while air is discussedherein as the working fluid within the hoist system 10, one skilled inthe art will recognize that other gases could also be used if requiredby the particular working environment.

Referring also to FIG. 3, the hoist 10 may be operated with the hoistcontrol pendant 14 to move the component 18 in either an up direction bydepressing the control button 46 or in a down direction by depressingthe control button 48 or in a down direction in a faster mode ofoperation by depressing the “quick release” control button 50. Theselection of either the up button 46, the down button 48 or the quickrelease button 50 controls the air flow within the pneumatic circuit.The hoist system 10 according to the disclosure herein increases theexhaust flow from the air balancer 12, thus improving the release timeof the handing device 17 from the component 18 and expediting thedownward movement of the cable 16, while not affecting the upwardmovement of the hoist system. This is accomplished, in general terms, bytemporarily bypassing the normal air exhaust 52 through the controlpendant 14 and providing a closer exhaust opening by way of exhaustvalve 68 mounted on the end wall 24 of the air balancer 12, as shown inFIG. 4. In a predetermined period of time after depressing the exhaustbutton, exhaust valve 68 exhausts a given volume of air more quicklythan the gas exhaust port 52 due to its close proximity to the airbalancer 12, thus obtaining a quicker release of the hoist system 10from the component 18 after it has been installed.

A better understanding of the gas flow through the pneumatic circuit maybe had by reference to the flow schematic shown in FIG. 5 and the airbalancer 12 shown in FIG. 4. Therein, it may be seen that pressurizedgas, such as air, is provided from a source 54 through an up/downcontrol block 56, and by activation of the up button 46 the gas passesinto the end the wall 24 of the air balancer 12 through air supply inlet58. This causes the piston 42 to move longitudinally through the housing20, thus causing the cable 16 to rotate and lift the component 18.

After the component 18 has been installed and it desired to lower thehoist system once again, the down button 48 is depressed or the quickrelease button 50 is depressed, which also simultaneously depressesbutton 48 due to the presence of a bridge 49 between the button 50 andthe button 48. If only the button 48 is depressed, gas will exhaust fromthe air balancer 12 via exhaust flow control fitting 80, and through thelength of exhaust flow path 82 and return to the control pendant 14 tobe expelled through exhaust port 52.

On the other hand, if no load is on the hoist, and the quick releasebutton 50 is depressed, the gas will be exhausted through nearby pilotvalve 68 having an exhaust opening 69 so as to increase the speed atwhich the air is exhausted and increase the release rate of the hoist.More particularly, an exemplary embodiment of the disclosure utilizes apilot valve 70, such as a dual pilot valve, to allow the quick releasebutton 50 to operate the exhaust valve 68, such as a three-way singleair pilot spring return valve or similar element. The dual pilot valve70 in combination with a load check device or switch 72 confirms thatthere is no load on the hoist 10 before allowing it to quickly descend.An air regulator 76, and more particularly, a relieving air regulator,is set to a predetermined pressure generally corresponding to no loadbeing on the hoist, i.e., the weight of the component 18 has beenremoved. Similar devices for pressure regulation, such as a pressuregauge for example, could also be used instead of the air regulator. Ifthe load check switch 72 determines the load 78 (i.e., pressure) fromthe hoist is less than the preset amount on the air regulator 76, thenthe pilot valve 70 allows the quick release button 50 to operate theexhaust valve 68. That is, the downward force on the lifting cable 16 isnot exerting a pressure greater than the predetermined pressure on theair balancer 12. The load at which the air balancer 12 allows the quickrelease 50 to operate is set through an empirical process. The load onthe hoist 10 is set and the air regulator 76 is adjusted until the hoist10 does not allow the quick release to be actuated when it is underload. The load is determined by the tension on the cable 16 fromwhatever is being lifted. The tension on the cable applies rotationalforce to the ball screw 32 in the air balancer 12 which applies a forceon the piston 42. The piston 42 compresses the air which then translatesto an air pressure increase.

The exhaust valve 68 defines an exhaust opening closer in proximity tothe air balancer 12 than the exhaust port 52 found on the controlpendant 14, which thus allows the gas within the air balancer 12 to berapidly dispelled and the lifting cable 16 lowered at a greater speed.Hence, the hoist release rate is increased and the process time for theassembly line is improved. A one-way check valve 66 is provided tofunction as a speed exhaust controller and facilitates the rapiddownward movement of the hoist in a smooth manner.

If the quick release button 50 is depressed, but there is a load 78 onthe hoist determined by the load check switch 72 to be greater than theset point of the air regulator 76, then the pilot valve 70 will not opento allow the gas to exhaust through the exhaust valve 68. Rather, thegas will be exhausted through the exhaust port 52 on the control pendant14 until the pressure on the hoist decreases to a value below the setpoint of the air regulator 76. Thereafter, when no load is on the hoistas evidenced by a pressure less than the set point of the regulator 76,the pilot valve 70 will then allow the release button 50 operate theexhaust valve 68.

In an exemplary embodiment of the disclosure, the hoist system 10further includes a ball valve 74 with a lock out screw 84 which allowsthe exhaust valve 68 to be manually by-passed if necessary duringcertain operations.

While various embodiments of the disclosure have been described, thedescription is intended to be exemplary, rather than limiting and itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the disclosure. Accordingly, the disclosure is not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

We claim:
 1. A hoist system comprising: an air balancer having an airsupply and an air exhaust; a lifting device; and a hoist control pendantto control supply and exhaust of pressurized air to and from the airbalancer, respectively, the hoist control pendant configured to controlvertical movement of the lifting device; wherein the air exhaust fromthe air balancer includes a first exhaust flow path through a firstexhaust opening and a second exhaust flow path through a second exhaustopening, the first exhaust flow path having a first length and thesecond exhaust flow path having a second length, the second length beingshorter than the first length.
 2. The hoist system according to claim 1,wherein the hoist control pendant includes an up control, a downcontrol, and a quick release control, wherein the down control isconfigured to be in fluid communication with the first exhaust flow pathand the quick release control is configured to be in fluid communicationwith the second exhaust flow path.
 3. The hoist system according toclaim 2, wherein the first exhaust opening is provided on the hoistcontrol pendant.
 4. The hoist system according to claim 3, furthercomprising an air exhaust system including a first pilot valve, a loadcheck switch, and a second pilot valve, the second pilot valve includingthe second exhaust opening.
 5. The hoist system according to claim 4,further comprising an air regulator set to a predetermined pressure,wherein the load check switch is configured to compare a pressureexerted by the lifting device to the predetermined pressure.
 6. Thehoist system according to claim 5, wherein, if the pressure exerted bythe lifting device is determined by the load check switch to be lessthan the predetermined value, the first pilot valve is configured suchthat actuation of the quick release control expels air within the airchamber through the second exhaust flow path.
 7. The hoist systemaccording to claim 6, wherein, if the pressure exerted by the liftingdevice is determined by the load check switch to be greater than thepredetermined value, the first pilot valve is configured such thatactuation of the quick release control expels air within the air chamberthrough the first exhaust flow path until the pressure exerted by thelifting device decreases to a value below the predetermined value. 8.The hoist system according to claim 1, further comprising a rotatablevalve to manually bypass the second exhaust flow path.
 9. The hoistsystem according to claim 1, wherein the second exhaust flow pathincludes a one-way check valve.
 10. An air balancer for a pneumatichoist system comprising: a housing including opposing end walls and acylindrical casing extending therebetween; a piston slidably disposedwithin the cylindrical casing so as to define an air chamber proximateone of said opposing end walls; a mechanical linear actuator extendinglongitudinally through the housing and actuated by the piston; an inletfor air to be supplied into the air chamber; and an exhaust systemcontrolling air to be exhausted from the air chamber; wherein theexhaust system defines a first exhaust flow path and a second exhaustflow path, the second exhaust flow path exhausting a greater volume ofair than the first exhaust flow path in a predetermined period ofelapsed time.
 11. The air balancer according to claim 10, wherein theexhaust system includes a load check device for determining if a loadfrom a pneumatic hoist is present.
 12. The air balancer according toclaim 11, wherein, if no load is determined to be present by the loadcheck device, the exhaust system is configured to expel air within theair chamber through the second exhaust flow path.
 13. The air balanceraccording to claim 12, wherein, if a load is determined to be present bythe load check device, the exhaust system is configured to expel airwithin the air chamber through the first exhaust flow path.
 14. The airbalancer according to claim 12, wherein the second exhaust flow pathincludes an exhaust valve disposed on said one of said opposing endwalls.
 15. The air balancer according to claim 11, wherein the exhaustsystem further includes a pilot valve, said pilot valve configured toopen when the load check device determines no load is present on thehoist.
 16. The air balancer according to claim 15, wherein the exhaustsystem further includes an exhaust valve, the exhaust system configuredto expel air through the exhaust valve when said pilot valve is open.17. A method of pneumatic hoist operation comprising: providing apneumatic hoist having an air balancer, a lifting cable hoist, and ahoist control pendant, wherein the hoist control pendant includes an updirection control, a down direction control, and a quick release downcontrol; actuating the up control on the hoist control pendant to raisethe lifting cable in an upwards direction; actuating the down control onthe hoist control pendant to lower the lifting cable in a downwardsdirection at a first rate of descent; actuating the quick releasecontrol on the hoist control pendant to lower the lifting cable in adownwards direction at a second rate of descent; wherein the second rateof descent is greater than the first rate of descent.
 18. The methodaccording to claim 17, wherein actuating the down control on the hoistcontrol pendant to lower the lifting cable in a downwards direction at afirst rate of descent includes exhausting air from the air balancerthrough a first exhaust flow path.
 19. The method according to claim 18,wherein actuating the quick release control on the hoist control pendantto lower the lifting cable in a downwards direction at a second rate ofdescent includes exhausting air from the air balancer through a secondexhaust flow path.
 20. The method according to claim 19, furthercomprising providing a load check device for determining if a load fromthe pneumatic hoist is present, wherein actuating the quick releasecontrol includes the load check device determining if the load from thepneumatic hoist is greater than a predetermined value.